1. Technical Field
The present invention relates to an ultrasound diagnosis apparatus, and more particularly to ultrasonic diagnosis technology for a fetal heart.
2. Related Art
Ultrasonic diagnosis of a fetus in it's mother womb has become commonplace in medical practice. One of the purposes of such diagnoses is to diagnose or treat congenital heart diseases at an early stage. If a serious heart disease can be diagnosed prior to delivery, it is often possible to successfully treat the disease using medicine, surgery, or the like immediately after childbirth. In ultrasonic diagnosis of a fetal heart, the shape or size of the heart is displayed on a tomographic image, or the state of blood flow in the heart is displayed on a two-dimensional color Doppler image (or a color flow mapping image). Also, according to the pulse Doppler method, Doppler information obtained from a sample gate (or a sample volume) which is set within the heart is subjected to frequency analysis, so that Doppler waves formed by the frequency analysis are displayed. Alternatively, it is also possible to use three-dimensional ultrasonic diagnosis technology to perform three-dimensional image forming or three-dimensional measurement with regard to the fetal heart.
JP 3045642 B describes processing of a two-dimensional ultrasonic image, and particularly describes processing for extracting the outline of the left ventricle in the heart to form an image such as a multi-ring. JP 2004-159997 A describes processing of a three-dimensional ultrasonic image, and particularly describes processing for extracting a heart chamber portion within the heart. JP 2000-197633 A discloses measurement and analysis of a cardiac valve signal of a fetus. Although this publication, JP 2000-197633 A, describes a method which uses an ultrasonic Doppler method, the publication does not describe technology of processing an image which represents a change in the shape of the heart such as a tomographic image and a three-dimensional image to thereby obtain information indicative of the motion of the heart. JP 11-221210 A describes technology of displaying a temporal change of the areas of a plurality of regions defined in the left ventricle in a plurality of graphs. JP 8-103442 A describes image processing technology for extracting the left ventricle as a closed region. None of the above-noted publications describes the technology of obtaining information which is an alternative to electrocardiographic information from the temporal change in the shape of the heart.
Generally, in ultrasonic diagnosis of the heart, an electrocardiograph is used to measure an electrocardiographic signal in real time, and the electrocardiographic signal is then used as information representing the period of motion of the heart or as a synchronization signal for measurement. However, it is not possible to bring a plurality of electrodes into direct contact with a fetus for obtaining an electrocardiographic signal. In this regard, ultrasonic diagnosis of a fetus in the womb suffers from a specific problem which would not arise in the normal ultrasonic diagnosis of the heart. As such, with regard to fetuses, it is difficult to obtain information concerning heartbeats (cardiac information) in the ultrasonic diagnosis of the heart, which makes it difficult to recognize the state of the heart or measure the heart functions.
Here, as the cardiac cycle of the fetal heart is much shorter than that of the adult heart, it is necessary to increase the frame rate (or the volume rate) when displaying the fetal heart in an ultrasonic image. However, if data transmission and reception based on the ultrasonic Doppler method described in JP 2000-197633 A indicated above is performed in addition to data transmission and reception for measuring or displaying the fetal heart as an ultrasonic image, the frame rate (or the volume rate) is inevitably reduced.